A colonic muco-submucosal elongated polyp (CMSEP) was identified at colonoscopy in a 53-year-old male patient with lower gastrointestinal bleeding. Non-polypoid depressed type of early cancer was noted at the tip of the colonic polyp. The CMSEP is very rare and incidentally found in most cases. Moreover, its association with colonic neoplasia is extremely rare. To our knowledge, this is the second case report of CMSEP associated with a cancerous transformation.